Failure sliding mode

Figure 11.9 The three modes of failure (a) opening mode, or mode I, characterized by (b) sliding mode, or mode II, (c) tearing mode, or mode HI,...

Susceptibility to interlaminar failure is a major weakness of advanced laminated composite materials. It can occur by in-plane shearing (i.e., sliding) (mode II). and out-of-plane shearing (i.e.. tearing) (mode III) as well as by tensile (mode I) deformation. Mode II loading is of particular interest, as values have been shown to correlate with compression after impact data [142.143]. which is required for such purposes as civil aircraft certification. 

Brittle solids fail in one of three possible modes, shown in Fig. 5.47. In mode I (the opening mode), both the crack plane and the direction of propagation are normal to the applied tension. In mode II (the sliding mode), a tensUe shear acts to slide the fracture planes over each other in the direction of stress. Mode IE (the tearing mode) is also a shear failure, except that the shear causes the fracture to propagate normal to the stress. Corresponding to these three modes, a material has three critical values of the stress intensity factor and... 

Fig. 4 Brittle failure modes of polystyrene within contacts, a Poly(styrene) film on a poly(methylmethacrylate) substrate. The regular crack pattern is induced by the sliding of a glass sphere under elastic contact conditions, b Poly(styrene) under viscoplastic scratching by a cone indenter (from [40])...

In recent experiments, the application of stress orthogonally to a shearing surface caused a ductile failure of brittle polymer (5, 6). In the first series (5), a variety of plastomers and elastomers were made to slide one on the surface of another, at a constant velocity of 215 cm/sec, under increasing normal loads. The wear characteristics of polymers, including several brittle ones such as PMMA and PS, depend on the applied normal stress. At relatively low pressure, almost no wear was observable, even under magnification the little observed was apparently brittle, ill-defined, microparticulate debris. At intermediate normal loads, 3 to 20 kg/cm2, roll formation was the dominant mode of wear. Such rolls appear on the surfaces of all uncrosslinked polymers whose Tg is below the test temperature and on amorphous and semicrystalline polymers whose Tg is above... 

Slide programs, CD-ROMs, posters, books, and videotapes on medication safety including such topics as Failure Mode and Effects Analysis (FMEA) timely and accurate educational sessions and conferences, slide programs, and presentations. 

Wear is the process of physical loss of material. In sliding contacts this can arise from a number of processes in order of relative importance they are adhesion, abrasion, corrosion and contact fatigue. Wear occurs because of local mechanical failure of highly stressed interfacial zones and the mode of failure is influenced by environmental factors. 

Figure 13.35 Basic modes of failure of structural materials ( ) opening or tensile mode (II) sliding or in-plane shear mode (III) tearing or antiplane shear mode.

Once a sharp crack has formed, it is possible to analyse its growth, using the concepts of fracture mechanics. The subject was developed for the failure of large metal structures. Linear elastic fracture mechanics, the simplest theory, considers the stress and strain fields around the crack tip in elastic materials. In the majority of cases, the crack faces move directly apart (mode I deformation in the jargon) rather than sliding over each other in... 

When the foundation is subjected to a horizontal load, there are at least three potential modes of sliding failure. The failure mode that develops depends primarily on the skirt height, the spacing and orientation of skirt elements, the net vertical foundation load, and... 

Five failure modes were observed, namely sliding, rocking, head/bed joints opening, cracking in bricks, and crashing of wall. Figures 7.9, 7.10, 7.11, 7.12, 7.13, and 7.14, show these failure modes. 

Fig. 7.10 Plastic strain and failure mode (0.25 MPa axial stress) (Wall sliding and rocking)... 

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